+++ /dev/null
- ===========================
- PNG: The Definitive Guide
- ===========================
-
- Source Code
-
-Chapters 13, 14 and 15 of "PNG: The Definitive Guide" discuss three free,
-cross-platform demo programs that show how to use the libpng reference
-library: rpng, rpng2 and wpng. rpng and rpng2 are viewers; the first is
-a very simple example that that shows how a standard file-viewer might use
-libpng, while the second is designed to process streaming data and shows
-how a web browser might be written. wpng is a simple command-line program
-that reads binary PGM and PPM files (the ``raw'' grayscale and RGB subsets
-of PBMPLUS/NetPBM) and converts them to PNG.
-
-The source code for all three demo programs currently compiles under
-Unix, OpenVMS, and 32-bit Windows. (Special thanks to Martin Zinser,
-zinser@decus.de, for making the necessary changes for OpenVMS and for
-providing an appropriate build script.) Build instructions can be found
-below.
-
-Files:
-
- README this file
- LICENSE terms of distribution and reuse (BSD-like)
-
- Makefile.unx Unix makefile
- Makefile.w32 Windows (MSVC) makefile
- makevms.com OpenVMS build script
-
- rpng-win.c Windows front end for the basic viewer
- rpng-x.c X Window System (Unix, OpenVMS) front end
- readpng.c generic back end for the basic viewer
- readpng.h header file for the basic viewer
-
- rpng2-win.c Windows front end for the progressive viewer
- rpng2-x.c X front end for the progressive viewer
- readpng2.c generic back end for the progressive viewer
- readpng2.h header file for the progressive viewer
-
- wpng.c generic (text) front end for the converter
- writepng.c generic back end for the converter
- writepng.h header file for the converter
-
- toucan.png transparent PNG for testing (by Stefan Schneider)
-
-Note that, although the programs are designed to be functional, their
-primary purpose is to illustrate how to use libpng to add PNG support to
-other programs. As such, their user interfaces are crude and definitely
-are not intended for everyday use.
-
-Please see http://www.libpng.org/pub/png/pngbook.html for further infor-
-mation and links to the latest version of the source code, and Chapters
-13-15 of the book for detailed discussion of the three programs.
-
-Greg Roelofs
-newt@pobox.com
-30 June 2001
-
-
-BUILD INSTRUCTIONS
-
- - Prerequisites (in order of compilation):
-
- - zlib http://www.gzip.org/zlib/
- - libpng http://www.libpng.org/pub/png/libpng.html
- - pngbook http://www.libpng.org/pub/png/book/sources.html
-
- The pngbook demo programs are explicitly designed to demonstrate proper
- coding techniques for using the libpng reference library. As a result,
- you need to download and build both zlib (on which libpng depends) and
- libpng. A common build setup is to place the zlib, libpng and pngbook
- subdirectory trees ("folders") in the same parent directory. Then the
- libpng build can refer to files in ../zlib (or ..\zlib or [-.zlib]),
- and similarly for the pngbook build.
-
- Note that all three packages are designed to be built from a command
- line by default; those who wish to use a graphical or other integrated
- development environments are on their own.
-
-
- - Unix:
-
- Unpack the latest pngbook sources (which should correspond to this
- README file) into a directory and change into that directory.
-
- Copy Makefile.unx to Makefile and edit the PNG* and Z* variables
- appropriately (possibly also the X* variables if necessary).
-
- make
-
- There is no "install" target, so copy the three executables somewhere
- in your path or run them from the current directory. All three will
- print a basic usage screen when run without any command-line arguments;
- see the book for more details.
-
-
- - Windows:
-
- Unpack the latest pngbook sources (which should correspond to this
- README file) into a folder, open a "DOS shell" or "command prompt"
- or equivalent command-line window, and cd into the folder where you
- unpacked the source code.
-
- For MSVC, set up the necessary environment variables by invoking
-
- %devstudio%\vc\bin\vcvars32.bat
-
- where where %devstudio% is the installation directory for MSVC /
- DevStudio. If you get "environment out of space" errors under 95/98,
- create a desktop shortcut with "c:\windows\command.com /e:4096" as
- the program command line and set the working directory to the pngbook
- directory. Then double-click to open the new DOS-prompt window with
- a bigger environment and retry the commands above.
-
- Copy Makefile.w32 to Makefile and edit the PNGPATH and ZPATH variables
- appropriately (possibly also the "INC" and "LIB" variables if needed).
- Note that the names of the dynamic and static libpng and zlib libraries
- used in the makefile may change in later releases of the libraries.
- Also note that, as of libpng version 1.0.5, MSVC DLL builds do not work.
- This makefile therefore builds statically linked executables, but if
- the DLL problems ever get fixed, uncommenting the appropriate PNGLIB
- and ZLIB lines will build dynamically linked executables instead.
-
- Do the build by typing
-
- nmake
-
- The result should be three executables: rpng-win.exe, rpng2-win.exe,
- and wpng.exe. Copy them somewhere in your PATH or run them from the
- current folder. Like the Unix versions, the two windowed programs
- (rpng and rpng2) now display a usage screen in a console window when
- invoked without command-line arguments; this is new behavior as of
- the June 2001 release. Note that the programs use the Unix-style "-"
- character to specify options, instead of the more common DOS/Windows
- "/" character. (For example: "rpng2-win -bgpat 4 foo.png", not
- "rpng2-win /bgpat 4 foo.png")
-
-
- - OpenVMS:
-
- Unpack the pngbook sources into a subdirectory and change into that
- subdirectory.
-
- Edit makevms.com appropriately, specifically the zpath and pngpath
- variables.
-
- @makevms
-
- To run the programs, they probably first need to be set up as "foreign
- symbols," with "disk" and "dir" set appropriately:
-
- $ rpng == "$disk:[dir]rpng-x.exe"
- $ rpng2 == "$disk:[dir]rpng2-x.exe"
- $ wpng == "$disk:[dir]wpng.exe"
-
- All three will print a basic usage screen when run without any command-
- line arguments; see the book for more details. Note that the options
- style is Unix-like, i.e., preceded by "-" rather than "/".
-
-
-RUNNING THE PROGRAMS: (VERY) BRIEF INTRO
-
- rpng is a simple PNG viewer that can display transparent PNGs with a
- specified background color; for example,
-
- rpng -bgcolor #ff0000 toucan.png
-
- would display the image with a red background. rpng2 is a progressive
- viewer that simulates a web browser in some respects; it can display
- images against either a background color or a dynamically generated
- background image. For example:
-
- rpng2 -bgpat 16 toucan.png
-
- wpng is a purely command-line image converter from binary PBMPLUS/NetPBM
- format (.pgm or .ppm) to PNG; for example,
-
- wpng -time < toucan.ppm > toucan.png
-
- would convert the specified PPM file (using redirection) to PNG, auto-
- matically setting the PNG modification-time chunk.
-
- All options can be abbreviated to the shortest unique value; for example,
- "-bgc" for -bgcolor (versus "-bgp" for -bgpat), or "-g" for -gamma.
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